I'm not on facebook, so I'll put my two cents worth here...
My first guess was that something was going on, in relation to the grommets. This sound is similar to what you get when you put pressure on the tone bar, killing vibrations. But since that wasn't an option, forget I mentioned it.
This note has the dull thud reminiscent of my Wurli 206 just before the middle Bb snapped, so perhaps it's a tine on it's last few strikes. However, I've never broken a tine, and I haven't replaced any due to loss of tone, so I really wouldn't know what to listen for to say whether or not it was the tine.
I guess the damper (arm? or just the felt?) is listed as a possibility, were it to be rubbing the tine just enough to kill any resonance. However, I think I'd expect something with a little more of a "buzz" sound to it, were that the case.
Not sure how a pedestal felt could effect the note, unless it fell off the ped, and somehow got between the hammer and the tine, dampening the note. I've seen the felts fall off the back of the 76/77 cams, but I can't say from this distance what year the piano is.
So for the heck of it, my first choice is to say it's a tip with a deep groove choking the note.
Tine replacement is my second guess.
Third choice is Gremlins.
Please keep in mind, I'm just a guitar player dabbling in Rhodes pianos, so my opinion is worth squat. If you are wagering on this outcome, do not use me to sway your opinion.
Ray